This invention relates to a lenticular stereographic projecting and recording method and an apparatus for implementing that method. More particularly, this invention relates to a stereographic projecting and recording method by which a plurality of images of different viewpoints are projected and recorded as linear picture elements, either simultaneously or sequentially in steps, on various light-sensitive materials, electronic photoreceptors or projection media such as screens through lenticular lenses. More specifically, the invention relates to a stereographic printing method for printing the linear picture elements on lenticular light-sensitive materials. Further, this invention relates to a lenticular stereographic projecting and recording apparatus, particularly to a stereographic printing apparatus for use in lenticular stereographic image projecting and recording, wherein a plurality of images of different viewpoints are projected either simultaneously or sequentially in steps and printed on lenticular light-sensitive materials as a number of broad linear picture elements. This invention also relates to a stereographic image projecting and recording method that is capable of achieving key subject matter matching in lenticular stereophotography, as well as a stereographic image projecting and recording apparatus. In particular the invention permits correct key subject matter matching by a simple procedure, is capable of forming an appropriate stereoscopic image (picture) and is simple in construction.
Methods are known that produce a stereoscopic view using a lenticular light-sensitive material formed of a lenticular sheet having a plurality of lenticular lenses and a light-sensitive layer. An example of the methods for producing such a stereoscopic view is shown in FIG. 31 (two-eye Process ). A lenticular sheet C composed of a number of lenticular lenses is provided on the back side with a light-sensitive layer D to form a lenticular light-sensitive material F. Image information from different viewpoints, namely, the left and right images A.sub.1 and A.sub.2, are projected onto the lenticular light-sensitive material F through projection lenses B.sub.1 and B.sub.2 so that they are separated into an array of linear picture elements for recording. When the recorded images are viewed with the left and right eyes L and R of an observer through the lenticular sheet C of the lenticular light-sensitive material F as shown in FIG. 32, they can be seen in relief (as a stereoscopic view). However, this method has the disadvantage that the positions of the observers eyes that insure the production of a stereoscopic view are very limited and if those positions are not attained, the optical density (hereunder referred to simply as "density") is reduced abruptly to impair the three-dimensional effect.
It is known that the above-described defects can be lessened by increasing in appropriate amounts the line width of linear picture elements formed in the lenticular sheet. Systems that have so far been proposed to meet this condition include: (1) an apparatus of the type described in Examined Japanese Patent Publication (kokoku) No. 607/1974, which makes a relative movement of the light-sensitive material by moving it and the projection lenses in the same direction at a predetermined speed ratio so as to increase the line width of linear picture elements; (2) an apparatus of the type described in Examined Japanese Patent Publication (kokoku) No. 33847/1978, which allows a lenticular light-sensitive material to rock about the longitudinal axis of the central lenticular lens through a predetermined range of angles; and (3) an apparatus of the type described in Examined Japanese Patent Publication (kokoku) No. 25902/1974, which adopts an additional lenticular sheet (lens) method in which recording is performed with the line width of linear picture elements being increased by means of a cover that is placed on top of the entire surface of the lenticular light-sensitive material in such a way as to modify the refractive power of the lenticular lens.
As described in Examined Japanese Patent Publication (kokoku) No. 33847/1978, the two-eye (two-frame or two-image) system which has two original images projected through a lens system to be printed on a lenticular light-sensitive material has the advantage that it permits two original images to be exposed simultaneously with a simple mechanism. However, the number of original images that can be printed is limited to two, so the distance between the two mirror images produced by an enlarging lens or lenses (projection lens or lenses) must be adjusted to be adjusted to be equal to the distance between the two eyes of the observer and so that the distance from the enlarging lens or lenses to the lenticular sheet is substantially equal to the viewing distance. Further, in the case of observing an exposed stereoscopic image, the distance that insures stereoscopic viewing is limited and even if the width of two linear picture elements included within the pitch of one lenticular lens in the lenticular sheet is increased, a gap tends to occur between images and a satisfactory three-dimensional (3D) effect cannot be achieved In addition, depending on the manner in which the viewpoints are shifted, an inverted stereoscopic image is likely to form. Another problem with the two-image system is that if one attempts to increase the line width of linear picture elements by the rocking method, the angle through which the lenticular light-sensitive material is increased so as to deteriorate the quality of the periphery of the stereoscopic image.
With a view to solving these problems, a multi-eye (multi-image or multi-frame) approach has been proposed but approach suffers from the disadvantage that the printing method is complicated and inefficient or that the printing apparatus is bulky and expensive. An example of the apparatuses that operate on multi-eye system is described in U.S. Pat. No. 3,953,869. The specification and the drawings (e.g., FIG. 4) of this patent illustrate an apparatus in which N spaced two-dimensional views are projected onto the light-sensitive layer of a lenticular light-sensitive material, of lenticule pitch W, through N spaced projecting lenses that are capable of changing the angle of projection, whereby N condensed images that are uniform and in focus are formed within the lenticular pitch of the lenticular light-sensitive material.
However, even this apparatus operating on the multi-eye system suffers from the above-mentioned disadvantage that the printing method is complicated and inefficient or that the printing apparatus is bulky and expensive. Stated more specifically, this apparatus completes the printing of original images at high speed since a multiple of original images are printed in one step by means of a multiple of projecting lenses. However, the multiple original images which are to be disposed in positions that insure predetermined angles of projection must be spaced apart by predetermined distances, so the individual films are separated from one another. Further, in order to insure that the projected views from the individual original images will be focused at desired angles of projection, it is necessary to provide a lens moving mechanism for adjusting the individual lenses and such a mechanism is complex. Another requirement is to increase the line width of linear picture elements, which adds to the complexity of the overall mechanism. In addition, printing original images as they are in a continuous form requires that those original images be prepared by means of a special camera in which the distance between lens is variable.
U.S. Pat. No. 4,101,210 discloses a stereoscopic image forming apparatus in which a plurality of original images spaced on a film carrier are illuminated with projecting light from a light source to form focused images through a lens system comprising a plurality of enlarging lenses on a lens carrier, thereby exposing the plurality of original images in a single step. However, even in this apparatus, there is a need for not only separating original stereographic images and arranging them in discrete rows on the film carrier but also arranging a plurality of lens systems in rows in correspondence with those original images. This involves cumbersome operations in preparing original images while, at the same time, the overall size of the apparatus is increased.
U.S. Pat. No. 4,650,282 describes a method of exposing a multiple of original images by which the central image within one pitch of small lenses in a lenticular light-sensitive material is made broader than the image on either end. However, this patent does not disclose any specific apparatus or means for implementing that method.
U.S. Pat. No. 4,814,826 discloses a method and an apparatus for effecting a three-dimensional print by a non-scanned exposure of a three-dimensional lenticular light-sensitive material without requiring lens movement. In the device disclosed therein a fixed periscopic lens and a periscopic optical unit including parallel mirrors that are rotatable about a first axis normal to the optical axis of the lens and a second axis intersecting said first axis, are positioned between the lenticular light-sensitive material and a film having a plurality of continuous frames thereon. The frames of the film are moved by a certain distance from the optical axis of the lens so as to create angular exposure zones, and the frames of the film corresponding to those angular exposure zones are illuminated with projecting light for delivering an image exposure of those frames of the film towards the periscopic optical unit along the center of each angular exposure zone. This apparatus, which allows the projecting lens to be fixed, obviates the need for performing the scanning process as in the prior art which involves changing the lens angle in response to the film movement and any translation offset of image from the optical axis of the lens that would otherwise develop on account of image exposure is eliminated by rotating the parallel mirrors about the two axes. However, the apparatus suffers from the disadvantage that if there are four frames to be exposed, four separate steps are necessary because the film must be moved for each frame, and the subsequent adjustment of mirrors followed by exposure must be repeated four times and the mirror unit is rotated in the same lens and mirror position in order to provide a predetermined printing angle for the image of each frame.
With reference to the images of frames obtained from different viewpoints, the images of objects at different depths are recorded in positions offset from the optical axis of each camera lens and the amount of offset is related to the change in the distance to each object. For a geometric presentation of this phenomenon, see FIG. 33. The amount of this offset is also related to the distance between taking lens and can be expressed by the following equations as disclosed in U.S. Pat. Nos. 3,953,869 and 4,120,562, supra: EQU e=kf/(k-f.sub.t) (1) EQU k'=se/k=sf.sub.t /(k-f.sub.t) (2) EQU a'=se/a=(k/a)k' (3) EQU b'=se/b=(k/b)k' (4)
where:
e is the distance from the center line 102 of the taking (lens the objective plane) 100 to the film plane 104; PA1 f.sub.t is the focal length of the taking lens 100; PA1 a, b and k are the distances from the center line 102 of the taking lens 100 to the objects A, B and K, respectively;
a',b' and k' are the distances along the film plane 104 from the longitudinal axis 106 to the images A',B' and K', respectively.
Thus, in order to produce an appropriate stereoscopic image by a method in which a plurality of original images as obtained from different viewpoints are projected and recorded on a lenticular light-sensitive material, it is necessary that the images of the key subject matter that are recorded in the respective frames, which are slightly offset from one another, be brought into registry on the plane of image projection so that an offset-free sharp image will be formed with respect to the key subject matter. However, this matching of the key subject matter cannot be accomplished in an easy and advantageous manner with the conventional apparatus using lenticular light-sensitive materials.
See, for example, Examined Japanese Patent Publication (kokoku) Nos. 607/1974, 33847/1978 and 25902/1974, supra. These patents do not disclose a specific method of accomplishing the matching of the key subject matter and the methods and apparatuses that are described in the patent references rely upon the operator's skill for bringing the projected images of the key subject matter into registry. In other words, no satisfactory stereoscopic image can be formed unless the operator is a skilled engineer.
U.S. Pat. No. 3,953,869, supra, discloses an apparatus for forming a stereoscopic image from three or more original images. In this type of apparatus, the matching of the key subject matter bears particular importance and the patent makes a reference to the offset of the object in the individual original images. However, the application of three or more original images increases the complexity of the apparatus and makes it more difficult to accomplish the correct matching of the key subject matter. Further, the apparatus disclosed in the patent under consideration does not have any advantageous means for solving these problems.
U.S. Pat. No. 4,903,069 discloses a stereographic printing apparatus that computes the distance of the key subject matter between adjacent original images on the basis of the object distance at the time of taking original images, the distance between taking lenses and the focal length of each taking lens, sets the travel distance (feed pitch) of original images in accordance with the thus calculated distance of the key subject matter, and moves the original images frame by frame so that the projected views of a plurality of original images are recorded on a lenticular light-sensitive material. However, this apparatus requires that the data of each frame of original images be recorded when shooting the object and that printing is performed with the feed pitch being varied for each frame of original images. Accordingly, the multi-lens camera is very expensive and complicated. In addition, the process of controlling the printing operation is also complex. Further, the efficiency of printing with this apparatus is low.